Characterization of Anisotropic Fracture Behavior of 7075-T6 Aluminum Alloy Sheet under Various Stress States

The anisotropic fracture of the 7075-T6 aluminum alloy sheet was investigated under various stress states. Tensile tests using specimens with various shapes were conducted along different loading directions to understand the anisotropic fracture behavior of the 7075-T6 sheet over a wide range of stress states. The failure strains as a function of loading directions and stress state were evaluated using the digital image correlation (DIC) technique. The fracture morphology was observed at the macroscale and microscopic to probe the failure model and fracture mechanisms of the 7075-T6 aluminum alloy sheet. The anisotropic fracture behavior of the alloy was described using a DF2016-based anisotropic fracture model. Meanwhile, the effect of plastic anisotropy on the formability of the 7075-T6 sheet was examined using both quadratic and non-quadratic yield functions. The constructed anisotropic fracture loci, fracture envelopes, and fracture forming limit diagrams reasonably characterized the anisotropic fracture behavior of the 7075-T6 sheet over a wide range of loading conditions.